Succinamic metal salts in turbine oil



United States Patent Ofilice 3,121,057 Patented Feb. 11, 1964.-

This invention relates to antirust compositions. It is more particularlyconcerned with mineral lubricating oil containing metal salts of certainamic acids.

As is well known to those skilled in the art, the rusting of ferrousmetal surfaces has been a common occurrence in the field of lubrication.This has been a serious problem in steam turbine lubrication,particularly during the initial operation of new installations. Rustingis most pronounced at points where the clearance between bearingsurfaces is very small, as in the governor mechanism. This is usuallycaused by water entering the oil supply, as by condensation, andbecoming entrained in the oil throughout the circulating system, therebycoming into contact with the ferrous metal surfaces. Manifestly, thisconstitutes a menace to the operational life of the turbine.

Many materials have been proposed as addition agents to impart antirustproperties to lubricating oils. Particularly in the case of rustprotection in the presence of sea water, as in marine turbinelubrication, most compounds used have been materials containing two ormore carboxylic acid groups (-COOH).

It has now been found that antirust properties in the presence of seawater can be imparted to lubricating oil by the addition of certainmonocarboxylic acid salts. It has been discovered that certainsuccinamic acid salts are effective antirust additives for turbine oils.

Accordingly, it is a broad object of this invention to provide novelrust inhibitors. Another object is to provide lubricating oils that areinhibited against rusting of ferrous metal surfaces in the presence ofsea water. A further object is to provide an antirust turbine oil containing a monocarboxylic acid salt rust inhibitor. A specific object isto provide metal salts of succinamic acids. A more specific object is toprovide antirust turbine oil containing certain succinamic acid salts.Other objects and advantages of this invention will become apparent tothose skilled in the art from the following detailed description.

In general, the present invention provides a mineral lubricating oilcontaining a small amount, sufficient to prevent rusting of ferrousmetal surfaces, selected from the group consisting of (1) group II metalsalts of an amic acid having the formula,

wherein R is a monovalent alkyl radical containing between about 18 andabout carbon atoms and having a tertiary carbon atom directly attachedto the nitrogen atom, (2) copper salts of an amic acid having theformula,

wherein R is a monovalent alkyl radical containing between about 18 andabout 30 carbon atoms and having 1 tertiary carbon atom directlyattached to the nitrogen atom, and (3) methoxy group II metal salts ofan amic acid having the formula,

wherein R is a monovalent alkyl radical containing between about 18 andabout 30 carbon atoms and having a tertiary carbon atom directlyattached to the nitrogen atom.

The addition agents utilizable in the improved lubricating oils of thisinvention are succinamic acid salts having the structural formula,

ii mLv-c-clncrn-o wherein R is an alkyl group containing between about18 and about 30 carbon atoms per alkyl group and having a tertiarycarbon atom directly attached to the nitrogen atom and M is a metal ofgroup II of the periodic chart of the elements. The amic acids that areconverted into the metal salts can be made by any method known in theart for preparing such compounds. Preferably, they are produced bywarming succinic acid anhydride with a tertiary-alkyl primary monoaminehaving between about 18 and about 30 carbon atoms per molecule. This canbe done readily by heating a mixture of equimolar amounts of the acidanhydride and the tertiary-alkyl primary amine at a temperature of -150C. for a period of time varying between one and 4 hours. The additionoccurs readily Without the formation of water. Lcss desirably, the amicacids can be prepared by the controlled reaction between equimolaramounts of succinic acid and the amine, with the elimination of one moleof water per mole of amie acid produced. Care must be exercised to avoidthe elimination of two moles of water to form the cyclic imide.

The amines utilizable in forming the amic acids are the tertiary-alkylprimary monoamines in which a primary amino group (NH is attached to atertiary carbon atom, and which contains between about 18 and about 30carbon atoms per tertiary-alkyl group. The amines all contain the group,

Non-limiting examples of the amines are t-dodecyl primary amine,t-tetradecyl primary amine, t-pentadecyl primary amine, t-hexadecylprimary amine, t-0ctadecy1 primary amine, t-eicosyl primary amine,t-tetracosyl primary amine, and t-triacontyl primary amine. These aminescan be prepared by several methods well known to those skilled in theart. Specific methods for preparing the t-allt'yl primary amines aredisclosed in the Journal of Organic Chemistry, vol. 20, page 295 et seq.(1955). Mixtures of such amines are contemplated. These can be made froma polyolefin fraction (e.g. polypropylene and polybutylene cuts) byfirst hydrating with sulfuric acid and water to the correspondingalcohol, converting J the alcohol to alkyl chloride with dry hydrogenchloride, and finally condensing the chloride with ammonia, underpressure to produce a t-alltyl primary amine mixture.

The salts contemplated herein are neutral salts of copper and group Hmetals and the methoxy metal salts of group 11 metals. The amido portionof both neutral and incthoxy salts must have at least about 18 carbonatoms and up to about 30 carbon atoms in the alkyl group attachedthereto.

The neutral salts of the succinamic acids contemplated herein are metalsalts wherein the salt-forming metal is copper or from group ll(including both 11A and 11B) of the periodic chart of the elements, asset forth in Introductory College Chemistry, by H. G. Deming (Jahn Wileyand Sons). Preferred salt-forming metals are Ba, Ca, Sr, Mg, and Zn. Themethod of forming the metal salts of this invention is not a criticalfactor herein. Thus, any of the usual methods known to those skilled inthe art can be utilized. Typical methods include forming an alkali-metalsalt (cg. by neutralizing with caustic). and then using a doubledecomposition reaction with a salt of the desired metal (cg. CaClneutralizing the acid with a metal alcoholate (cg. barium methylate);and heating with an oxide of the metal (e.g. magnesium oxide). Suitably,non-polar solvents can be used in the salt-forming operation. Thus,concentrates of the salts or" this invention in amounts varying betweenabout 10 percent and about 90 percent, by weight, in a solvent arccontemplated. Such concentrates are then added to the turbine oil togive the desired final concentration in the lubricant. Suitable solventsare lubricating oils.

The methoxy metal salts contemplated herein are made from metals ofgroup ll (including both HA and 11B) of the periodic chart of theelements. They can be prepared by eating equimolar amounts of the amicacid and metal methortidc (methylate). Temperatures in the order of ll50C. are suitable for the neutralization reaction. Generally, a diluent isdesirable and filtration of the product may be desired.

The antic acid salts contemplated herein are ettective to impartantirust properties to mineral lubricating oils, particularly highlyrefined mineral lubricating oils, such as, steam turbine oils. Theamount of amic acid salt that is added to the lubricating oil will varybetween about 0.001 percent and about 10.0 percent, by weight, of theoil. In preferred practice, amounts varying be tween about 0.05 percentand about 1.0 percent, by weight. are used. ()thcr substances can beadded to the lubricating oil to impart other properties thereto. Forexample, there may be added antioxidants, pour point depressants, V.l.improvers, and El. agents.

The following specific examples are for the purpose of illustrating theantirust lubricants of this invention and of demonstrating theeffectiveness thereof. It is to be understood that this invention is notto be limited to the particular reactants employed, or to the operationsand manipulations described therein. Other reactants, as describedhcieinbefore, can be employed, as those skilled in the art will readilyunderstand.

The amine reactants used in the examples are a mixture or" pure amines.Amine i is a mixture of tertiary allryl primary amines averaging 18 to24 carbon atoms per molecule and averaging about carbon atoms permolecule. it has a tertiary carbon attached to the NH group. Itcontains, by weight, about 4-0 percent t-octayl primary amine, aboutpercent t-eicosyl primary airline, about 15 percent t-docosyl primaryamine, about 10 percent ttetracosyl amine. and a small amount, less than5 percent, other amines as high as t-triacontyl primary amine.

EXAMPLE 1 was stirred at 95 C. for '1 hours to form the Amir Analysis:

Estimated Found Percent Mg 1. 3-; I 1.41) Percent N 1. 7 1. 57

EXAMPLE 2 A mixture of 50 gms. (0.5 mole) of succinic anhydride, 150gms. (0.5 mole) of Amine B and 150 cc. of xylene was stirred at C. for 2hours to form the Amine B succinamic acid. To the above Amine Bsuccinamic acid was added at room temperature with stirring 20 gms. (0.5mole) NuOH previously dissolved in 200 cc. of methanol. The mixture wasgradually heated to 175 C. to form the sodium salt of the Amine Bsuccinamic acid. To the Na salt of the Amine B succinamic acid was thenadded 420 gms. of light lubricating oil and 33 gms. (0.25+5 grns.excess) of CaCl previously dissolved in 200 cc. of methanol. The mixturewas gradually heated to l75 C. and was held there for 3 hours to insurethe complete formation of the Ca salt. The reaction product was filteredthrough filtering clay. The final product, the calcium salt of the AmineB succinamic acid, which contains 66% light lubricating oil was fluid atroom temperature.

Analysis:

1 Estimated Found lcrccnt (a 1.85 1.57 Percent N 1. 32 1. l2

EXAMPLE 3 A mixture of 50 grns. (0.5 mole) of succinic anhydride, gms.(0.5 mole) of Amine B and 150 cc. of toluene was stirred at 95 C. for 2hours to form the Amine B succinamic acid. To the above Amine Bsuccinarnic acid was added at 50 C. with stirring 286 gms. of 12% Bamcthylate solution (0.25 mole of Ba). The mixture was gradually heatedto C. The reaction product being viscous, was diluted with 468 gms. oflight lubricating oil and filtered through filtering clay. The finalproduct, the Bu salt of the Amine l3 succinamic acid, which contained66% light lubricating oil was fiuid at room temperature.

Analysis:

Estimated Found Percent Ba 4. 5s 2. 33 Percent. N 0. J 0. till EXAMPLE 4A mixture of 50 gms. (0.5 mole) of succinie anhydridc, 150 gms. (0.5mole) of Amine B and 150 cc. of xylene was stirred at 95 C. for 2 hoursto form the Amine B succinamie acid. To the above Amine l3 succinamicacid was added at room temperature with. stirring 20 gms. (0.5 mole) ofNaOH previously dissolved in 250 cc. of methanol. The mixture wasgradually heated to 175 C. form the Na salt of the Amine B suecinamicacid. To the Na salt of the Amine l3 t mic acid was tlrm. added at roomtemperature airing 432 grns. of light lubricating oil and 44 gms. (0.25rnole+l gms. excess) of ZnCl previously dissolved in 250 cc. ofmethanol. The mixture was 'radually heated to 175 C. and was held at 175C. for 3 hours to insure the complete formation of the Zn salt of theAmine B succinamic acid. The product was filtered through filteringclay. The final product which contained 66% light lubricating oil wasfluid at room temperature.

Analysis:

Estimated Found Percent Zn 2. 2. 01 Percent N 1. 08 1. 08

EXAMPLE 5 A mixture of 50 gms. (0.5 mole) of succinic anhydride, 150gms. (0.5 mole) of Amine B and 206 gms. of light lubricating oil washeated at 100 C. for 2 hours with stirring to form the Amine Bsuccinamic acid. To the Amine B succinamic acid was added 14.6 gms.(0.25 mole) of magnesium hydroxide at room temperature with stirring.The mixture was gradually heated to 175 C. and was held at 175 C. for 30minutes. The reaction product was filtered through filtering clay. Thefinal product, the Mg salt of Amine B succinamic acid, which contained50% light lubricating oil was fluid at room temperature.

Analysis:

I Estimated Found Percent Mg 1. 4 1, 28 Percent N 1. 7 1. 52

EXAMPLE 6 A mixture of 50 gms. (0.5 mole) of succinic anhydride, 150gms. (0.5 mole) of Amine B and 206 gms. of light lubricating oil washeated at 95100 C. for 2 hours with stirring to form the Amine Bsucoinamic acid. To the Amine B succinamic acid was added 10.08 gms.(0.25 mole) of magnesium oxide at room temperature with stirring. Themixture was gradually heated to 175 C. and was held at 175 C. for 2hours. The reaction prodnot was filtered through filtering clay. Thefinal products, the Mg salt of Amine B succinarnic acid, which contained50% light lubricating oil was clear and fluid at room temperature.

Analysis:

Estimated Found Percent Mg 1.4 1. 24 Percent N 1. 7 1. 58

EXAMPLE 7 A mixture of 50 gms. (0.5 mole) of succinic anhydride, 150gms. (0.5 mole) of Amine B and 100 cc. of benzene was heated at 95 C.for 2 hours with stirring to form the Amine B succinamic acid. The AmineB succinamic acid, diluted with 215 grns. of light lubricating oil, wasadded at room temperature with stirring to 11.5 grns. (0.5 mole) ofsodium in the form of a sodium methylate solution. The mixture wasgradually heated to 175 C. to form the sodium salt of Amine B succinamicacid. To the Amine B succinamic salt was added at room temperature withstirring 69 gms. (0.25 mole+6.5 gms. excess) of CuSO .5H O dissolved in1000 cc. of methanol. The mixture was gradually heated to 175 C. and washeld at 175 C. for 2 hours. The reaction product was filtered throughfiltering clay. The final product, the cupric salt of Amine B succinamicacid, which contained 50% light lubricating oil was dark-green in colorand fluid at room temperature.

Analysis:

Estimated Found EXAMPLE 8 A mixture of 50 gms. (0.5 mole) of succinicanhydride, 150 gms. (0.5 mole) of Amino B and 100 cc. of

cnzene was heated at 95 C. for 2 hours with stirring to form the Amine Bsuccinamic acid. The Amine B succinamic acid, diluted with 464 gms. oflight lubricating oil, was then added at room temperature with stirringto the zinc methylate solution prepared from 23 gms. (1 mole of sodiumin the form of a sodium methylate solution and 88 gms. (0.5 mole+20 gms.excess) of Zinc chloride dissolved in 300 cc. of methanol. The mixture,being heated gradually with stirring to distill out the methanol,started to thicken at about C. A quantity of 9 cc. of water addeddrop-wise made the reaction mixture fluid again. The reaction mixturewas slowly heated to 150 C. and held at 150 C. for 30 minutes. Thereaction product was then filtered through filtering clay. The finalproduct, the methoxy Zinc salt of Amine B succinamic acid, whichcontained 66 /392; light lubricating oil was clear and fluid.

Analysis:

[ Estimated Found Percent. Zn Percent N EXAMPLE 9 A mixture of 50 gms.(0.5 mole) of succinic anhydride, 150 gms. (0.5 mole) of Amine B and 100cc. of benzene was heated at C. for 2 hours with stirring to form theAmine B succinamic acid. The Amine B succinamic acid, diluted with 424gms. of light lubricating oil, was then added at room temperature withstirring to 12.12 gms. (0.5 mole) of Mg in the form of a Mg methylatcsolution. The mixture was gradually heated to 150 C. and was held at 150C. until all the methanol and benzene distilled over (about 2 hours).The final product, the methoxy Mg salt of Amine B succinamic acid, whichcontained 66 /69?) light lubricating oil, was clear and fluid at roomtemperature.

Analysis:

Estimated Found EXAMPLE 10 Nine mineral oil blends were prepared. Eachblend contained a small amount of one of the additives described inExamples 1 through 9. The base oil used is a highly solvent-refinedmineral lubricating oil having 31 API gravity and a Saybolt Universalviscosity of 150 seconds at F. This is a typical steam turbinelubrieating oil. These blends were subjected to the ASTM rust testD665-44T using synthetic sea water. The composition of each blend andtest results are set forth in Table I.

The test method used to distinguish the rusting characteristics oflubricating oil blends was the ASTM test D66544T for determining RustPreventing Characteristics of Steam Turbine Oils in Presence of later,in which synthetic sea water was used. The synthetic sea water contained25 grams of sodium chloride, 11 grams of magnesium chloride hexahydrate,4 grams of sodium sulfate, and 1.2 grams of calcium chloride per liter.In this test a cylindrical polished steel specimen is suspended andsoaked in 300 cubic centimeters of the oil under test at 140 F. forthirty minutes. Thirty cubic centimeters of synthetic sea water areadded and the mixture is stirred at 1000 rpm. After 48 hours, the steelspecimen is removed and examined for evidence of rust on the portion ofthe specimen which hangs in the oil. in order to pass this test, thetest specimen must be entirely free of rust.

Table I l (one'n, ASTM Additive t Exarnple Wt. Hurt Test percent Resultmore It will be apparent to those skilled in the art that the metalsalts and methoxy metal of these succinamic acids are eifective toimpart antirust properties to lubricating oils, in the presence of seawater. Thus, the mineral oil compositions are highly effective forsevere service, such as, in marine turbine lubrication.

Although the present invention has been described with preferredembodiments, it is to be understood that modifications and variationsmay be resorted to, without departing from the spirit and scope of thisinvention, as those skilled in the art will readily understand. Suchvariations and modifications are considered to be within the purview andscope of the appended claims.

What is claimed is:

1. A mineral lubricating oil containing a small amount, based on theweight of said oil and sullicient to inhibit said oil against rusting offerrous metal surfaces, of a metal salt selected from the groupconsisting of (l) wherein R is an alkyl group containing between about18 and about 30 carbon atoms per alkyl group and having a tertiarycarbon atom directly attached to the nitrogen atom and M is selectedfrom the group consisting of copper and metals of group II of theperiodic chart of the elements; and (2) wherein R is an alkyl groupcontaining between about 18 and about 30 carbon atoms per alltyl groupand having a tertiary carbon atom directly attached to the nitrogen atomand M is a metal of group It of the periodic chart of the elements.

2. A mineral lubricating oil containing between about 0.001 percent andabout percent, by weight of the lubricant, of a metal salt selected fromthe group consisting of (1) R11NC*CII2C li2(/O ll ll wherein R is analkyl group containing between about 18 and about carbon atoms per alkylgroup and having a tertiary carbon atom directly attached to thenitrogen atom and M is selected from the group consisting of copper andmetals of group 11 of the periodic chart of the elements; and (2)wherein R is an alkyl group containing between about 18 and about 30carbon atoms per alkyl group and having a tertiary carbon atom directlyattached to the nitrogen atom and M is a metal of group 11 of theperiodic chart of the elements.

3. A mineral lubricating oil containing between about 0.05 percent andabout 1.0 percent, by weight of the lubricant, of a metal salt havingthe structure,

wherein R is an alkyl group containing between about 18 and about 24carbon atoms per alkyl group and having a tertiary carbon atom directlyattached to the nitrogen atom.

4. A mineral lubricating oil containing between about 0.05 percent andabout 1.0 percent, by weight of the lubricant, of a metal salt havingthe structure,

wherein R is an alkyl group containing between about 18 and about 24carbon atoms per alkyl group and having a tertiary carbon atom directlyattached to the nitrogen atom.

5. A mineral lubricating oil containing between about 0.05 percent andabout 1.0 percent, by weight of the lubricant, of a metal salt havingthe structure,

wherein R is an alkyl group containing between about 18 and about 24carbon atoms per alkyl group and having a tertiary carbon atom directlyattached to the nitrogen atom.

6. A mineral lubricating oil containing between about 0.05 percent andabout 1.0 percent, by weight of the lubricant, of a metal salt havingthe structure,

wherein R is an alkyl group containing between about 18 and about 24carbon atoms per alkyl group and having a tertiary carbon atom directlyattached to the nitrogen atom.

7. A mineral lubricating oil containing between about 0.05 percent andabout 1.0 percent, by weight of the lubricant, of a metal salt havingthe structure,

wherein R is an alkyl group containing between about 18 and about 24carbon atoms per alkyl group and having a tertiary carbon atom directlyattached to the nitrogen atom.

8. A mineral lubricating oil containing between about 0.05 percent andabout 1.0 percent, by weight of the lubricant, of a metal salt havingthe structure,

wherein R is an alkyl group containing between about 18 and about 24carbon atoms per alkyl group and having a 9 tertiary carbon atomdirectly attached to the nitrogen atom.

9. A mineral lubricating oil containing between about 0.05 percent andabout 1.0 percent, by weight of the lubricant, of a metal salt havingthe structure,

RlIN|(|2CH CIlzfi-O-Mg0CH wherein R is an alkyl group containing betweenabout 18 and about 24 carbon atoms per alkyl group and having 10 atertiary carbon atom directly attached to the nitrogen atom.

References Cited in the file of this patent UNITED STATES PATENTS2,490,744 Trigg et a1 Dec. 6, 1949 2,604,451 Rocchini July 22, 19522,640,812. Bryant June 2, 1953 2,756,213 Dixon July 24, 1956 UNITEDSTATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 l2l O57February ll 1964 Paul Y, C, Gee et al.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 2, lines 24 to 27 the lower right-hand portion of the formulashould appear as shown below instead of as in the patent:

OMOCH same column 2 lines 55 to 60 the formula should appear as shownbelow instead of as in the patent:

column 3 line l l for "J'ahn" re ad John column 4 line "(3 for 1T5 Coform" read 175 CD to form column 7, lines 45 to 48 the formula shouldappear as shown below instead of as in the patent:

O u RHN C-CH CH -C -M Signed and sealed this 30th day of June 1964.

(SEAL) Attest:

ERNEST W, SWIDER EDWARD J. BRENNER Attesting Officer Commissioner ofPatents

1. A MINERAL LUBRICATING OIL CONTAINING A SMALL AMOUNT, BASED ON THEWEIGHT OF SAID OIL AND SUFFICIENT TO INHIBIT SAID OIL AGAINST RUSTING OFFERROUS METAL SURFACES, OF A METAL SALT SELECTED FROM THE GROUPCONSISTING OF (1)